The research continues to study mechanisms of stimulation of gastric secretion from the parietal and peptic cells by histamine, gastrin and the vagus by measuring dose response constants (Vmax, Km and threshold) using receptor occupancy theory as the basis for analyzing the data. Studies will also be made of interactions between different stimuli and between various stimuli and specific inhibitors, e.g. cimethidine, an antagonist to the gastric H-2 receptor, or atropine, anatogonist to the vagus, and prostaglandins, inhibitors of cAMP systems. These studies will be done in gastric fistula dogs before and after fundic vagotomy and after complete vagotomy. Similar studies will be done in patients with duodenal ulcer who require surgery who will be treated with either fundic vagotomy or truncal vagotomy. The receptor patterns of the various agents will thus be determined for both the peptic and parietal cell, innervated and denervated. By these means we hope to further study the role of the vagus in the pathophysiology and treatment of duodenal ulcer.